2.6.27-stable review patch. If anyone has any objections, please let us know.

------------------From: Jens Axboe <jens.axboe@oracle.com>

commit 78f707bfc723552e8309b7c38a8d0cc51012e813 upstream.

The above commit added WRITE_SYNC and switched various places to usingthat for committing writes that will be waited upon immediately aftersubmission. However, this causes a performance regression with AS and CFQfor ext3 at least, since sync_dirty_buffer() will submit some writes withWRITE_SYNC while ext3 has sumitted others dependent writes without the syncflag set. This causes excessive anticipation/idling in the IO schedulerbecause sync and async writes get interleaved, causing a big performanceregression for the below test case (which is meant to simulate sqlitelike behaviour).